The Center for HIV RNA Studies (CRNA) will focus on determining the structural and mechanistic bases of HIV-1 RNA dependent replication functions at the cellular, viral and atomic levels. Although considerable progress has been made over the past 25 years in understanding how proteins function in HIV-1 replication, comparatively little is known about how HIV-1 RNA structure, dynamics, trafficking, and interactions with proteins enable virus replication. Although HIV-1 RNA is exceptionally rich in biological functions, the paucity of detailed mechanistic insight into how these biological functions are executed is due to inherent difficulties in studying the structure and dynamics of RNA molecules. For example, it has been challenging to obtain high-resolution structural information for RNA and protein-RNA complexes using traditional X-ray crystallographic, NMR or cryo-electron microscopic approaches. It has also been difficult to study the functions and interactions of RNA molecules with proteins in vitro and in cells. The CRNA consists of a multidisciplinary team of structural biologists, chemists, cell and computational biologists, molecular biologists and virologists, many of whom are leaders in the study of HIV-1 RNA and the role of its structures in virus replication. They have developed and will further advance new approaches to overcome current technological obstacles, enabling mechanistic determination of the role of HIV-1 RNA structures and associated proteins in viral transcription, splicing, translation, packaging, particle assembly and interactions with restriction factors. The studies proposed herein will enable the CRNA to advance goals of clinical relevance, including the development of novel antiviral compounds, design of new strategies for the reactivation of latent proviruses, and the augmentation of host defenses against HIV infection. These studies will also result in the development of novel techniques that can be applied to all areas of RNA biology.